Optical apparatus for flight trainers



Aug. 8, 1950 R. C. DEHMEL OPTICAL APPARATUS FOR FLIGHT TRAINERS FiledApril 5. 1948 INVENTOR. Zfzk/zard CIT-97111261 Patented Aug. 8, 1950{UNITED PATENT OFFICE OPTICAL APPARATUS FOR "I LIGHT TRAINERS Richardcan miss, Sh01tt.Hills,.N..J.

'appucauonnprn 5, 1948, Serial No. 18,887

This invention relates to rgroundltrainers for aircraft pilots and moreparticularly to trainers 20f the type having optical means forsimulating visual flight conditions by'm'eans of views crimagesprojected upon a "screen,

Claims. (01. 35-42) It has been proposed to train aircraft pilots -by*means of optical apparatus arranged to project terrestrial views on ascreen in front of the pilot so as to simulate visual conditions attake-off and landing and other maneuvers.

thereby training the pilotin"his-operation of the controls-by means ofhis visualreactions.

"Modern flight training however places considerable emphasis oninstrument or blind dying and the present invention is intended mainlyto supplemen'tblind flying technique by introducing sufficient realismso that thestudent pilot maybe acquainted with common flight-conditions,such as for example those experienced in flying through broken cloudsfor a material length of time.

Under such conditions, the pilot is aware of the relative speed of theaircraft and he also can note a materialrate of change in the directionof the craft'from the speed and directionoflig'ht and shadow'flashingbya't opposite sides respec- :tively of the cockpit cowling.

An object of this invention therefore is to provide improved opticalapparatus eithe -aforesaid type 'forthe training of aircraft pilots,andparticularly for supplementing training in' blind flying, arranged sothat rela'tiveair speed, turns,

"pitch and roll through broken clouds mist and the like arerealistically simulated.

The invention will be'morefully set forth "in the following descriptionreferring to the accom- 'panying drawingpand the features ofnovelty willbe pointed out with particulari ty in the claims annexed to and forminga part ofthis specification.

Referring to the drawing the single fi'gure ithereof is a partlydiagrammatic view in perspective of flight trainer opticalapparatusembcdyin-g the present invention.

The invention comprises generally a translucent screen l which may beconveniently formed of frosted glass as part ofthe forward cockpit,icowling of the trainer on which images are pro- -jected by opticalapparatus including transparency means 'such as diapositive "elements #2a and B. These elements are controlled primarily in accordance with"simulated air speed as by means of a motor 4 andalsolin accordance with*simuj The projec- 'ti'on apparatus generally is controlled inaccordance with the pilots operation of the aircraft :controls so as tosimulate roll, b'ank and pitch,

diapos'itives and reflecting mirrors. (equivalent type 'prism 9 fortransmitting light "flectors and screen I.

,lated change in direction by apparatus presentlzs described. Theprojection apparatus :may comprise light sources '5 and'li disposedadjacent the .diapositive elements respectively, reflecting surfaces land :8 located .atthe opposite sides of the diapositives in line withthe respective :light source and focusing objective lenses l0 and I0suitably mounted in spaced relationbetween-the A Dove, or

from the reflecting surfaces according to simulated maneuvers ispositioned between the re- The rays of light from ithesprism areprojectecl-by means of a corrected projection lens '9' on both the rightand left sides of the cockpit cowling which is located a suitabledistance from the prism as indicated.

In the specific embodiment of my invention illustrated the diapositiveelements 2 and 3 are formed as circular bands supported by Webs i l and$2 from normally vertically positioned shafts Hi and M respectively.Each diapositivemaybe composed of a suitable transparency such as aphotographic film having cloud images or the like so as to project-apattern of light and shadow.

"The light sources 5 and "6 comprise electric lamps Ising movement Ofthe image across the receiving end of -the prism, i. e. from left torightlooking toward the screen, taking for example diapositive 3.Subject matter of this :general character 'is disclosed and claimed inmy Patent No. 2,474,096 granted-June 21, 19.49, for Optical TrainingApparatus.

As'the Dove prism in the position shown'does not-reverse the mo-vementofa projected image 'as tot-he horizontal direction, and since theprojec-tion lens 9' completely reverses the image it will be seen thatrotation of the diapositi've 3 in a clockwise direction as indicated forexample, and rotation of the diapositive 2 in counterclockwise directioncause the images in light and shadow from diapositive 3 to fall on theright side (R) of the cowling and the images fromdiapositire 2 "to fallon the left side (L) of the :cowling,

pivoted supporting brackets those in black and white and in color.

The diapositives 2 and 3 are controlled in accordance with pitch andturn maneuvers in addition to air speed, and for this purpose a pair ofi5 and I6 are mounted in fixed bearings l1 and I8 respectively forsupporting a gear differential l9 and a pair of shafts 20 and 2|connected to the difierential and by the gearing 22 and 23 tothediapositive elements 2 and 3 respectively. The shafts 20 and 2| aretubular so as to rotate freely on the brackets l5 and it and havesecured to their ends adjacent each other the drive gears 24 and 25 ofthe differential, planetary gears 26 and 21 of the differential beingfreely mounted on a spindle 28 which is secured at its opposite ends todiametrically opposite sides of a ring gear 29. The teeth at the outersurface of the ring gear are in mesh with a pinion 33 that is secured toa shaft 3| driven by a motor 32. The motor 32 is positioned according tosimulated turning movement of the aircraft and is suitably mounted onthe bracket l6, as by means of a supporting clamp 33. The shaft 3! atits overhanging end is supported in a bearing 35- that is similarlymounted by a clamping support 35 on bracket IS. The brackets l5 and 16are therefore interconnected for unitary pivotal movement so that theassembly can be tilted b means of a positioning motor 36 which isenergized in accordance with simulated rate of pitch of the aircraft.

For the purpose of mounting the diapositives 2 and 3 for tilting insimulation of pitching about the common center line of the bracketpivots at I! and 18, the shaft i3 is mounted in a fixed socket bearing31 for universal movement therein, and the other shaft I4 is connectedthrough a universal joint 38 with a drive shaft 39 that is in turnconnected to the air speed motor 4 through a suitable gear reducer 4d.The bearing 31 and the universal joint 38 are disposed along theaforesaid common center line so that operation of the pitch motor 36tilts the diapositives as a unit about said center line. Operation ofthe air speed motor at a rate corresponding to simulated air speeddrives the diapositive 3 directly through shaft 39 and the 'diapositive2 indirectly through the gearing 23,

shaft 2|, gear differential l9, shaft 20, and gearing 22. It will beapparent that when the rate of turn motor 32 is stationary therebyindicating flight along a straight line the gear differential functionsas a direct connection so that the diapositives 2 and 3 rotate at thesame speed. In case of turn, either to the right or to the left, theturn motor rotates the ring gear 29 of the differential in acorresponding direction so as to increase or decrease the speed ofrotation of diapositive 2. Thus the effect of a turn is simulated byimages flashing past one side of the cowling at a greater rate than atthe opposite side, i. e. at the inside of the turn. As previouslyindicated, pitching in either vertical direction is simulated'in thesame manner by the images flashing either generally in upward ordownward direction along the cowling.

For'the purpose of simulating roll the Dove prism 9 is suitablyconnected through gearing 4| 4 tea positioning motor 42 that isenergized in accordance with the simulated rolling of the aircraft.Since the prism when rotated also rotates the projected image the rollmaneuver can be readily simulated in this manner. In view of the factthat the Dove prism rotates the image at twice the speed of rotation ofthe prism, the gearing 4| is designed to rotate the prism at half speedof that of the shaft of the'roll motor 42. In the specific applicationshown, cloud images and the like are involved so that it is immaterialthat the images are inverted. If it is desired that the images be shownin true relation, a second prism can be used in series with prism 9 inthe manner disclosed in my aforesaid Patent No. 2,485,435. V

The control system for the air speed and other positioning motors is notshown in this application in the interest of clearness since adisclosure thereof is unnecessary for a complete understanding of thepresent invention. A system that may be used is disclosed in my PatentNo. 2,366,603

' issued January 2, 1945, for Aircraft Training Apparatus." For example,the air speed motor 4 may .be operated in the manner of the motor ASM,Fig. '7 of the aforesaid patent, the rate of turn motor 32 according tothe energization of the, rate of turn meter 2, Fig. 3 of the patent, andthe pitch and roll motors '36 and 42 according to the energization ofthe corresponding pitch and roll circuits, Figs. 6 and 4 respectively ofthe patent. It will beapparent that torque amplifiers of any suitabletype may be used where necessary to supply sufficient control torque.

It should be understood that this invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled inthe artwithout departing from the spirit of the invention.

What is claimed is:

1. Flight training apparatus comprising a translucent screenrepresenting the forward cowling of a cockpit, a pair of diapositiveelements each having images in light and shadow, means for jointlyrotating said diapositive elements in opposite directions in accordancewith simulated air speed, and light projection means associated withsaid elements V respectively for projecting images in a pair ofchannels, one for each diapositiveelement, on opposite sides of saidcowling generally in a direction toward the rear thereof so as tosimulate relative air speed.

2. Flight training apparatus comprising a screen representing theforward cowling of --a cockpit, a pair of diapositive elements eachhaving images in light and shadow, means including differentialapparatus for moving said diapositive elements indirection and speed inaccordance with simulated air speed and direction, and lightprojection'means associated with said elements respectively forprojecting said images on opposite sides of said cowling away from thecenter thereof soas to simulate relative air speed and change indirection.

3. Flight training apparatus comprising a translucent screenrepresenting the forward cowling of a cockpit,a pair of diapositiveelements each having images in light and shadow,

-jecting said images on opposite sides of said cowling generally awayfrom the center thereof so as to simulate relative air speed and changein direction through broken clouds and the like.

4. Flight training apparatus for student pilots comprising a translucentscreen approximately concave in form with respect to the position of thepilot so as to represent the forward cowling of a cockpit, a pair ofdiapositive elements formed as circular bands each having images inlight and shadow, means including diflerential apparatus for rotatingsaid elements in opposite directions and at different speeds inaccordance with simulated air speed and rate of turn, means forcontrolling the position of said elements in accordance with simulatedpitch, and light projection means associated with said elementsrespectively and controlled in accordance with simulated roll forprojecting said images on opposite sides of said cowling generally in adirection toward the rear thereof so as to simulate relative air speed.

5. In flight training apparatus having individual means for simulatingair speed and rates of turn, pitch and roll respectively and a screenrepresenting the forward cowling of a cockpit, projection apparatus forprojecting on said screen images in light and shadow for simulatingflight through broken clouds and the like as distinguished from fixedterrestrial images, said projection apparatus comprising a pair ofdiapositive means arranged to be moved according to operation of saidair speed simulating means, means for modifying the respective movementsof said diapositive means according to actuation of said rate of turnmeans, means for also controlling the position of said diapositive meansaccording to actuation of said rate of pitch means and optical structurefor directing said images along a pair of channels, one for eachdiapositive means, on opposite sides of said screen res-pectively inopposite directions generally away from the center of said screen andtoward the rear 6 thereof, said optical structure including a prismmovable about its longitudinal axis according to actuation of said rateof roll means.

6. Flight training apparatus comprising a screen representing theforward cowling of a cockpit, said screen being of approximately concaveform with respect to the position of the pilot in said cockpit,diapositive means having images in light and shadow, optical apparatusincluding a light source arranged with respect to said diapositive meansso as to project said. images in a pair of channels on opposite sides ofsaid cowling respectively, means for moving said dia positive meansaccording to simulated air speed so that the projected images on saidscreen move generally in a direction toward the rear thereof so as tosimulate movement through broken clouds and the like, and meansoperatively related to the aforesaid diapositive means and opticalapparatus representing rates of simulated turn, pitch and rollrespectively for modifying the movement of said images on said screenaccording to respective changes of said rat-es.

RICHARD CARL DEHMEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,987,625 Karnes Jan. 15, 19352,307,840 MacDonald Jan. 12, 1943 2,352,101 Hutter June 20, 19442,385,095 McCarthy Sept. 13, 1945 2,409,938 Hutter Oct. 22, 19462,413,633 Jones Dec. 31, 1946 2,453,436 Hertz Nov. 9, 1948 2,474,096Dehmel June 21, 1949 OTHER REFERENCES Aviation Week, p. 19, Jan. 19,1948.

